It certainly is - but with a much narrower intended scope of use. It's really not intended as a data transport mechanism for example. It's also homologous with JSON, XML is more flexible in its data representation. And finally, it makes use of HTML5 conventions, such as prefixing custom tags with a hyphen delimited string, data-* attributes etc.
I've been awkwardly saying "Aitch Five Oh En" in my head, but my work colleague says "Aitch Son", which even though it's a 5 and not an S sort of makes sense given the relationship to JSON :)
I'm reading Speaker for the Dead on a real, physical book at the moment, after buying and reading Ender's Game on Kindle. Why? Because Amazon won't sell me the Speaker ebook in my region - but they're happy to sell me books 1, 3 and 4. Well done guys.
Firefox 14.0.1, Windows 7 x64. Grey line is visible for a split second as page loads then disappears. EDIT: well now this is bizarre - it disappears and reappears as I scroll.
I thought the same until I saw that it was a research product/experiment. I think that makes it interesting and harmless rather than sad and misguided.